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Application of BDRM Theory in the Two-AXIS Underwater Channel 被引量:1
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作者 张林 笪良龙 卢晓亭 《Marine Science Bulletin》 CAS 2007年第2期12-17,共6页
Two-axis underwater channel often exists in deep ocean. Because of the coupling between surface channel and SOFAR channel, sound propagation in the two-axis underwater channel is complex and so its calculations of aco... Two-axis underwater channel often exists in deep ocean. Because of the coupling between surface channel and SOFAR channel, sound propagation in the two-axis underwater channel is complex and so its calculations of acoustic fields are difficult. The beam-displacement ray-mode (BDRM) theory is a normal mode method for propagation modeling in the common horizontally stratified shallow water. We improve the theory, proposing a new method for computing the upper boundary reflection coefficient, and apply it to calculate the acoustic fields of two-axis underwater channel. Transmission losses in the two-axis underwater channel are calculated by the BDRM theory. The results are in good agreement with the KRAKEN code and the computational speed excels those of the other methods. 展开更多
关键词 two-axis underwater channel BDRM theory reflection coefficient phase-shift correction
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A Novel Roll Compensation Method for Two-Axis Transportable Satellite Antennas 被引量:3
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作者 Laiding Zhao Jidong Xie +1 位作者 Xiaodong Bai Zhicheng Qu 《China Communications》 SCIE CSCD 2018年第3期137-148,共12页
Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme cond... Two-axis transportable satellite antennas(TATSAs) have been widely adopted owing to its simple structure and low cost. However, by searching in a wide range, it will take a very long searching time. Under extreme conditions, it will even fail to work. In this paper, we propose a novel roll compensation(RC) method for the low-cost TATSAs to achieve faster tracking even if when the antenna has no azimuth sensor. By analyzing the influence of roll axis on the system performance, details of the compensation method are derived. Simulation and measurement results indicate that the proposed RC method can effectively reduce the initial searching time for satellite communication. In addition, tracking along with the ellipse path with the RC method provides the highest tracking efficiency. 展开更多
关键词 two-axis transportable satelliteantenna (TATSA) satellite tracking roll com-pensation (RC) searching time.
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Sound propagation in two-axis underwater channel based on beam-displacement ray-mode theory
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作者 张林 笪良龙 卢晓亭 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2007年第3期300-303,共4页
Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theo... Sound propagation in a deep ocean two-axis underwater channel is often complex and difficult to simulate between surface channel and sound fixing and ranging (SOFAR) channel. The beam-displacement ray-mode (BDRM) theory is a normal mode method for propagation modeling in horizontally stratified shallow water. An improved method for computing the upper boundary reflection coefficient in the BDRM is proposed and applied to calculate the acoustic fields of a two-axis underwater channel. Transmission losses in the two-axis underwater channel are calculated in the new BDRM. The corresponding results are in good agreement with those from the Kraken code, and furthermore the computed speed of the new BDRM excels the other methods. 展开更多
关键词 two-axis underwater channel BDRM theory reflection coefficient phase-shift correction
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Tunable two-axis spin model and spin squeezing in two cavities
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作者 俞立先 李彩凤 +3 位作者 樊景涛 陈刚 张天才 贾锁堂 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第5期31-37,共7页
Multi-mode cavities have now attracted much attention both experimentally and theoretically. In this paper, inspired by recent experiments of cavity-assisted Raman transitions, we realize a two-axis spin Hamiltonian H... Multi-mode cavities have now attracted much attention both experimentally and theoretically. In this paper, inspired by recent experiments of cavity-assisted Raman transitions, we realize a two-axis spin Hamiltonian H = q(J_x^2+ χJ_y^2) + ω_0J_z in two cavities. This realized Hamiltonian has a distinct property that all parameters can be tuned independently. For proper parameters, the well-studied one- and two-axis twisting Hamiltonians are recovered, and the scaling of N^(-1) of the maximal squeezing factor can occur naturally. On the other hand, in the two-axis twisting Hamiltonian, spin squeezing is usually reduced when increasing the atomic resonant frequency ω_0. Surprisingly, we find that by combining with the dimensionless parameter χ(-1), this atomic resonant frequency ω_0 can enhance spin squeezing greatly. These results are beneficial for achieving the required spin squeezing in experiments. 展开更多
关键词 two-axis spin model spin squeezing two cavities
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Research of the Data Processing Method in Two-Axis Servo Drift Testing
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作者 郭素云 田自耘 +1 位作者 李东林 张宏伟 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1996年第1期34-37,共4页
The theory and algorithm of Singular Value Decomposition(SVD) is introduced.The advantage of Singular Value Decomposition used in system identification is studied,compared and illustrated through analyzing the data of... The theory and algorithm of Singular Value Decomposition(SVD) is introduced.The advantage of Singular Value Decomposition used in system identification is studied,compared and illustrated through analyzing the data of navigational gyroscopes drift in two-axis servo testing. 展开更多
关键词 ss:Gyroscope DRIFT SINGULAR Value DECOMPOSITION two-axis SERVO
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Endoscopic Optical Doppler Tomography Based on Two-Axis Scanning MEMS Mirror
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作者 王东琳 郝蕴琦 +4 位作者 翟凤潇 杨坤 刘洪琼 陈巧 谢会开 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第12期5-9,共5页
We study the feasibility of endoscopic optical Doppler tomography with a micro-electro-mechanical system(MEMS) mirror based probe. The additional phase shifts introduced by the probe are tracked and formulated.The sup... We study the feasibility of endoscopic optical Doppler tomography with a micro-electro-mechanical system(MEMS) mirror based probe. The additional phase shifts introduced by the probe are tracked and formulated.The suppression method of the probe phase shifts is proposed and validated by fluid flow detection experiments.In vivo blood flow detection is also implemented on a hairless mouse. The velocities of the blood flow in two directions are obtained to be-8.1 mm/s and 6.6 mm/s, respectively. 展开更多
关键词 Endoscopic Optical Doppler Tomography Based on two-axis Scanning MEMS Mirror
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Polymer/Ceramic Composite Membranes and Their Application in Pervaporation Process 被引量:6
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作者 刘公平 卫旺 +1 位作者 金万勤 徐南平 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第1期62-70,共9页
Pervaporation(PV),as an environmental friendly and energy-saving separation technology,has been received increasing attention in recent years.This article reviews the preparation and application of macroporous ceramic... Pervaporation(PV),as an environmental friendly and energy-saving separation technology,has been received increasing attention in recent years.This article reviews the preparation and application of macroporous ceramic-supported polymer composite pervaporation membranes.The separation materials of polymer/ceramic composite membranes presented here include hydrophobic polydimethylsiloxane(PDMS) and hydrophilic poly(vinyl alcohol)(PVA),chitosan(CS) and polyelectrolytes.The effects of ceramic support treatment,polymer solution properties,interfacial adhesion and incorporating or blending modification on the membrane structure and PV performance are discussed.Two in-situ characterization methods developed for polymer/ceramic composite membranes are also covered in the discussion.The applications of these composite membranes in pervaporation process are summarized as well,which contain the bio-fuels recovery,gasoline desulfuration and PV coupled proc-ess using PDMS/ceramic composite membrane,and dehydration of alcohols and esters using ceramic-supported PVA or PVA-CS composite membrane.Finally,a brief conclusion remark on polymer/ceramic composite mem-branes is given and possible future research is outlined. 展开更多
关键词 polymer/ceramic composite membrane PERVAPORATION bio-fuel recovery solvent dehydration PV cou-pled process
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Relativistic density functional investigation of UX_6(X=F,Cl,Br and I) 被引量:1
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作者 张云光 李育德 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第3期274-280,共7页
The molecular structures and the vibrational frequencies of uranium hexahalides UX6 (X=F, Cl, Br and I) molecules are investigated by using local density approximation (LDA) and generalised gradient approximation ... The molecular structures and the vibrational frequencies of uranium hexahalides UX6 (X=F, Cl, Br and I) molecules are investigated by using local density approximation (LDA) and generalised gradient approximation (GGA) functions (BP, BLYP and RPBE) in combination with two different relativistic methods (scalar and scalar+spin-orbit relativistic effects). The calculated results show that the differences are trivial between scalar and scalar+spin-orbit relativistic methods. The vibrational frequencies are also compared with existing experimental values, and overall, the RPBE approach gives the smallest error. The bond dissociation energies (BDEs) of UX6 are computed by using the RPBE function, thereby obtaining exact vibrational frequencies. In addition, the calculated magnitudes of the spin orbit effect on the BDE of UX6 (X=F, Cl, Br, and I) are found to be approximately -0.3198, 0.3218, -0.3609 and -0.4415 eV, respectively. 展开更多
关键词 molecular structure vibrational frequencies bond dissociation energy spin-orbit cou-pling
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A study on coupling technique and implementation of the wave-circulation coupled model 被引量:1
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作者 张志远 Liu Li +5 位作者 Zhou Yufeng Zhang Cheng Li Ruizhe Chen Yushu Song Guojie Yang Guangwen 《High Technology Letters》 EI CAS 2014年第1期82-87,共6页
The coupler is fundamental for a coupled model to realize complex interactions among component models.This paper focuses on the coupling process of Wave-Circulation(W-C) coupled model which consists of MASNUM(key labo... The coupler is fundamental for a coupled model to realize complex interactions among component models.This paper focuses on the coupling process of Wave-Circulation(W-C) coupled model which consists of MASNUM(key laboratory of marine science and numerical modeling wave model)and POM(Princeton Ocean Model).The current coupling module of this coupled model is based on the inefficient I/O file,which has already become a performance bottleneck especially when the coupled model utilizes a large number of processes.To improve the performance of the W-C model,a flexible coupling module based on the model coupling toolkit(MCT) is designed and implemented to replace the current I/O file coupling module in the coupled model.Empirical studies that we have carried out demonstrate that our online coupling module can dramatically improve the parallel performance of the coupled model.The online coupling module outperforms the I/O file coupling module.When processes increase to 96,the whole process of EXP-C takes only 695.8 seconds,which is only 58.8%of the execution time of EXP-F.Based on our experiments under 2D Parallel Decomposition(2DPD),we suggest setting parallel decomposition strategies automatically to component models in order to achieve high parallel efficiency. 展开更多
关键词 coupling technique model coupling toolkit (MCT) W-C coupled online cou-pling module 2D Parallel Decomposition (2DPD) parallel performance
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The WKBZ mode approach to sound propagation in the two-axis underwater channel
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作者 YAN Jin ZHANG Renhe (National Laboratory of Acoustics, Chinese Academy of Sciences Beijing 100080) 《Chinese Journal of Acoustics》 1997年第3期273-281,共9页
The two-axis underwater channel often exists in deep ocean. Sound propagation in the two-axis underwater channel is a benchmark problem for computational methods of underwater acoustics. In this paper, the generalized... The two-axis underwater channel often exists in deep ocean. Sound propagation in the two-axis underwater channel is a benchmark problem for computational methods of underwater acoustics. In this paper, the generalized phase-integral (WKBZ) normal mo de approach is extended to deal with this kind of problem. Numerical results show that the extended WKBZ approach is effective. 展开更多
关键词 MODE ZHANG The WKBZ mode approach to sound propagation in the two-axis underwater channel
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A new two-axis solar tracker based on the online optimization method:Experimental investigation and neural network modeling
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作者 Amir Pouya Masoumi Vahid Bagherian +1 位作者 Ali Reza Tavakolpour-Saleh Elham Masoomi 《Energy and AI》 2023年第4期341-359,共19页
This article presents a new two-axis solar tracker based on an online optimization algorithm so as to track the position of the sun without using its movement model.In this research,four well-known optimization algori... This article presents a new two-axis solar tracker based on an online optimization algorithm so as to track the position of the sun without using its movement model.In this research,four well-known optimization algorithms are employed to find the two unknown parameters named azimuth and zenith angles,which determine the position of the sun.The magnitude of the sunray is considered as the cost function of all algorithms.Then,several experiments are carried out to find the best optimization algorithm with optimal population size,number of iterations,and also the best initialization method.Uniform initialization leads to faster convergence compared to random initialization.The results clearly show that the particle swarm optimization algorithm with a population size of 15 and 7 iterations using uniform initialization method has better performance than the other algorithms,with a convergence time of less than 40 s.The average fitness value or voltage received by the tracker is 2.4 Volts in this method,which is higher than other methods.TLBO also performs well with a population size of 15 and 7 iterations.Afterward,the artificial neural network with one hidden layer and 20 neurons is employed to predict these two parameters in each day and moment in a year in Shiraz city according to the experimental data extracted from PSO.Number of the day from January and the time are inputs and zenith and azimuth angles are considered the output of neural network modeling.The performance of the proposed ANN model is evaluated using regression plots,demonstrating a strong correlation between predicted and target outputs.Finally,the outcomes reveal the feasibility of using online optimization algorithms and neural network modeling in an effort to bypass the complex mathematical model of mechatronic systems and predict the movement of the sun automatically. 展开更多
关键词 Intelligent two-axis solar tracker Optimization algorithm Particle swarm optimization algorithm Online optimization method Artificial neural network
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Rapid eutectic growth during free fall 被引量:7
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作者 Wenjing Yao Xiujun Han Bingbo Wei 《Chinese Science Bulletin》 SCIE EI CAS 2002年第15期1316-1320,共5页
Rapid eutectic growth of Sb-24%Cu alloy is realized in the drop tube during the free fall under the con-tainerless condition. Based on the analysis of crystal nuclea-tion and eutectic growth in the free fall condition... Rapid eutectic growth of Sb-24%Cu alloy is realized in the drop tube during the free fall under the con-tainerless condition. Based on the analysis of crystal nuclea-tion and eutectic growth in the free fall condition, it is indicated that, with the increase of undercooling, microstruc-tural transition of Sb-24%Cu eutectic alloy proceeds from lamellar to anomalous eutectic structure. Undercoolings of 0 -154 K have been obtained in experiment. The maximum undercooling exceeds to 0.19TE. Calculated results exhibit that Cu2Sb compound is the primary nucleation phase, and that the primary Sb dendrite will grow more rapidly than the eutectic structure when undercooling is larger than 40 K. The eutectic coupled zone around Sb-24%Cu eutectic alloy leads strongly to the Cu-rich side and covers a composition range from 23.0% to 32.7%Sb. 展开更多
关键词 DROP tube MICROGRAVITY EUTECTIC growth EUTECTIC cou-pled zone high undercooling.
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Effect of grain refinement on cutting force of difficult-to-cut metals in ultra-precision machining 被引量:1
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作者 Renjie JI Qian ZHENG +7 位作者 Yonghong LIU Hui JIN Fan ZHANG Shenggui LIU Baokun WANG Shuaichen LU Baoping CAI Xiaopeng LI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第3期484-493,共10页
The nickel-based superalloy Inconel 718 is treated with Coupled Ultrasonic and Electric Pulse Treatment(CUEPT),and the surface grain is refined from the average size of 9550.0 nm to287.9,216.3,150.5,126.3,25.8 nm by d... The nickel-based superalloy Inconel 718 is treated with Coupled Ultrasonic and Electric Pulse Treatment(CUEPT),and the surface grain is refined from the average size of 9550.0 nm to287.9,216.3,150.5,126.3,25.8 nm by different effective treatment currents,respectively.The ultraprecision turning experiments are carried out on the processed workpiece after CUEPT.The experimental results show that the average cutting force increases with the decrease of surface grain size.Moreover,a mathematical model that can describe the relationship between grain size and cutting force is established,and the calculated results match the experimental results well.The calculated results also indicate that the variation of cutting force caused by the same variation of grain size decreases as the degree of grain refinement increases.Finally,the influence mechanism of grain refinement on cutting force is analyzed.The improvement of stability of grain boundaries and the increase of number of grain boundaries cause the increase of cutting force after grain refinement. 展开更多
关键词 Grain size Cutting force Difficult-to-cut metals Grain refinement Ultra-precision machining cou-pled ultrasonic and electric pulse treatment
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Approximation for Counts of 2-runs in a Two State Markov Chain
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作者 Hui CHEN Mei ZHANG 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2013年第10期1907-1916,共10页
We consider a Markov chain X = {Xi, i = 1, 2,...} with the state space {0, 1}, and define W = ∑1=1^x XiXi+1, which is the number of 2-runs in X before time n + 1. In this paper, we prove that the negative binomial ... We consider a Markov chain X = {Xi, i = 1, 2,...} with the state space {0, 1}, and define W = ∑1=1^x XiXi+1, which is the number of 2-runs in X before time n + 1. In this paper, we prove that the negative binomial distribution is an appropriate approximation for LW when VarW is greater than EW. The error estimate obtained herein improves the corresponding result in previous literatures. 展开更多
关键词 Negative binomial distribution head run Stein's method total variation distance cou-pling
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